Tearing tester



A. ELMENDORF.

TEARING TESTER.

APPLlCATlON FILED FEB. 3. 1920.

1,423,841. atent d July 1922.

2 SHEETS- T I.

A. ELMENDORF.

'[EARING TESTER.

APPLICATION HLED FEB: 3,. 1920.

1 ,428,84 1 Patented July 25, 1922.

2 SHEETS-SHEET 2.

Z6 m. will] I' F H 1 jzya I the material acted parts ARMIN ELMENDORF, OFMADISON, W1SCONSIN.

TEARING TESTER.

all

Specification of Letters Yatent.

Patented July 25, 1922.

Application filed February 3, 1920. Serial No. 356,078.

To all whom it may concern:

Be it known that citizen of theUnited States of America, residin atMadison, in the county of Dane and tate ofWisconsin, have inventedcertain new and useful Improvements in Tearing Testers, of which thefollowing is a specification. i

y invention relates to a device for the purpose of testing the tearingstrength of paper, fabrics, rubber, materials. v I

An object of my invention is the construction of a device that willmeasure the tearing strength of materials by determining the worknecessary to accomplish the tearing.

Tearing testing devices hav constructed to measure directly the tearingforce. Such devices, however, are unreliable because of the non-uniformstructure of upon. A further object of my invention, therefore, is theconstruction of a device to remedy this defect by measuring the workdone in tearing the material acted upon.

A further object of my device is to utilize a calibrated-wheel with apendulum to determine the tearing force fromthe swing of the pendulumfrom one side of the vertical.

to the other side thereof.-

In my invention a uniform size of material is-selected to be tested. Theuse of a piece of material of certain size enables me,

in accordance with my invention, to make the calculations by which thestrength of.

materialsican be accurately determined.

In order to accomplish these and other objects, I have embodied myinvention in a device which is illustrated in the accompalryingdrawings, in which,

1 Figure 2 is a side elevation thereof; Figure 3is a front elevation ofthe gripping device used to hold the material;

4 is a side elevation thereof; Figure 5 is a front elevation showing apart only of a modified form of device, the

broken away being similar to those shown in Figure 1;

6' is a top plan view of the matetested, which is shown cut but notFigure arts Figure rial to be folded;

Figure 7 is a side elevation of the material in position to be torn;

Figure 8 e usually, been I gure 1 is a front elevation of my device is afront elevation of theygrip- I, ARMIN ELMnNnonr, a

leather, and other .zero mark.

oted in the usual manner.

ping means used with the modified form of device; and Figure 9 is a sideelevation thereof. Referring to the accompanying drawings, a frame 1 hasattached thereto a wheel 2 in any of the usual ways, as by an axis 3. Apart of this wheel is a pendulum 4. on the end of which is a wei ht 5.Extending from this frame is a guide arm 6 which has a doubleright-angled curve at the top thereof with the outer part 7 extendingdownwardly. Placed on the same shaft with the wheel is a pointer 8 whichis mounted frictionally onthe shaft so that it will not be moved readilto which itis pushed manually why the movement of the wheel. Thedownward turn of the arm has a screw 9 therein which may be adjustedtomove the pointer to the the frame of the device is an As a part ofangled end therearm 10 having on the right of, 10 a screw elevating andlowering means 11 in the upper part 12 of which is a pin 13. The weight5 has a projection 14 thereon in which is an opening, not shown, toreceive the pin. This pin has a flange 15 to prevent its removal fromthe upper part of the elevatin and lowering means.

Attached .to t e inner rim 16 of the wheel 2, which is grooved as shownat 17, is a belt or cord 18 attached by any. convenient method such as apin 19 as shown. The lower end of this cord. has attached thereto agripping member 20 composed of two parts. The part 21 may be removedfrom the part 22 in order to insert a portion of the material to betested between the parts thereof. On eachend of the part 21 is pivoted alatch 23 which may be attached to the part 22 by inserting the latchover a pin 24 in a groove the base of the machine by any convenientgripping the material. This consists of a body part 26 in which is ahandle 27 piv- The material is inserted in this gripping the handlethereof and placing the material within the jaw 28. The material is thenclamped by pressing down the handle.

The frame may position, if necessary, screws 29.

The face of the wheel maybe calibrated by means of the thumb 25in thelatch. Attached to device by raising beplaced in a horizontal in anydesired manner. As shown, a zero mark and a calibration ninety degreeseach wa therefrom are shown.

1 counterweight 30 attached to the wheel in any suitable manner, as by acord 31 attached to a pin 32, is used to balance the weight of the cord18 and the means to at tach said cord to the specimen of material to betorn.

The specimen of material 33 to be tested is cut as indicated at 34c. Thepart 35 is placed in the part of the clamp attached to the cord, whilethe parts 36 are inserted in the part attached to the base of thedevice. The specimens may be of any desired suitable size, but I haveshown a specimen which is two inches in width from the ends of the out.

In the modified form of device shown in Figure 5, I have provided meansfor swinging the pendulum over a greater angle than it can be swung inthe form illustrated in Figure 1. An arm 38 attached to the frame hassecured to the free end thereof a curved guide means 39. This guide isattached to the frame as shown at 1. The pendulum by means of this guidemay be swung from approximately 25 to approximately 90. The means tohold the pendulum in the modified form of the device consists of asliding mem-. ber 40 which may bestopped as desired on the guide 39 bythe thumb screw 40. The pendulum is held in this form by a pin asdisclosed in Figure 1.

An abutting means 41 is placed so that the right-hand side thereof willcause the pointer to be at zero when the pendulum is vertical. The formof device disclosed in Figure 5 may be used to tear paper and similarlight materials in which the angle through which the 'pendulum'swings isgreater than is required for heavier materials. 4

With the modified form of device, I clamp the material to be tested bymeans of a spring clamp 42 having jaws 43 having emery paper 44 or.other suitable means attached to the faces thereof to hold the materialto be tested.

A holder 45 is secured to the base of the device by screws 46 to holdthe specimen to be tested. This holder may have emery paper 47 attachedto the clamping faces thereof. The spring clamp, cord and counterweightare attached to the device in the same way as similar parts are attachedto the wheel shown in Figure 1.

The operation of my device may be described as follows:

The pendulum to which the weight is attached is moved over to the leftof the vertical to any desired angle and is held in position by theholding means while the angle to the left of the vertical is read. Thisangle is obtained by moving the pointer from zero to the stop. The paperor other ma- 1 ,aaasai terial to be tested is then fastened bythegripping means, after which the holding pin is removed, allowing thependulum to swing to the right of the vertical and tear the specimen.The stop pushes the pointer to the right as the pendulum swings to theright of the vertical, and, due to the friction of the bearingof thepointer on the shaft, the pointer remains in the position indicating thefarthest swing to the right of the vertical. The distance from thecenter of the axis of rotation to the center of gravity may be denotedby a, and the weight of the entire pendulum, including the weight, by W.Now let 6, be the initial angle, or the angle to the left, and 6, be thefinal angle, or the angle to the right,then the work done in tearin thespecimen is given by the expression vd (cos 6 -cos 6,). Dividing by thelength of the tear, which is two inches, gives the average force exertedduring the tear.

Having described my invention, what I claim is:

1. In a device of the kind described, means for testing the strength ofmaterial, comprising a wheel, a pendulum connected to said wheel, meansfor mounting the wheel to permit said wheel to turn and said pendulumtoswing, means adapted to hold the material to be tested, a connectionbetween said wheel and said holding means, means to hold said pendulummeans to release said pendulum allowing the movement of said pendulum totear the material to be tested, and indicator means adapted toco-operate with said wheel.

2. In a device of the kind described, means for holding the material tobe tested, rotating means connected to said holding means to tear thematerial to be tested, and means co-operating with said holding and saidrotating means to measure the work done in tearing the .material to betested.

- 3. In a device of the kind described. a frame, a clamp for holding thematerial to be tested, a wheel mounted on said frame to rotate to tearthe material to be tested. a connection between said wheel and saidclamp and means co-operating with said holding and said rotating meansto measure the work done in tearing the material to be tested.

4. In a tearing tester, a frame, a wheel mounted to rotate on an axis onsaid frame, the circumference of said wheel being calibrated, means torotate said Wheel comprising a weighted pendulum, means to determine theangle from the vertical said pendulum is swung and means to vary theangle to the left of the vertical said pendulum may be swung.

5. In a tearing tester, a frame, a wheel mounted to rotate on an axis onsaid frame,

means to rotate said wheel, means to hold assen the material to betested, a connection between said wheel and said holding means and meanson said wheel to counter-balance said connection means between saidwheel and said holding means.

6. In a tearing tester, a frame, a wheel mounted to rotate on an axis onsaid frame, the circumference of said wheel being calibrated, means torotate said wheel comprising a weighted pendulum, means to holdmateri'al to be tested, a connection between said wheel and said holdingmeans and an indicator mounted on an axis on said frame and adapted toco-operate with said calibrated wheel.

7. In a tearing tester, a frame, a wheel mounted to rotate on an axis onsaid frame, the circumference of said wheel being calibrated, means torotate said wheel comprising a weighted pendulum, means to hold thematerial to be tested, a connection between said wheel and said holdingmeans, means on said wheel to counter-balance said connecting meansbetween said wheel and said holding means, an indicator mounted on anaxis on said frame and adapted to co-operate with said calibrated wheeland means attached to said frame to adjust said indicator.

In testimony whereof I aflix my signature.

' ARDEN ELMENDORF.

